This invention relates to the field of enhanced 9-1-1 (E9-1-1) emergency services networks, and, more specifically, to an E9-1-1 system that facilitates the transition from the current circuit-switched emergency services networks to a full-featured voice over Internet protocol (VoIP) emergency services networks.
The National Emergency Number Association (NENA) has developed a specification for delivering emergency services calls from VoIP networks into the current circuit-switched emergency services networks (called “i2”). In accordance with this specification, a VoIP communications device originates an emergency services call by sending a call initiation request to a call server. The call initiation request includes the telephone number (TN) of the calling VoIP communications device and either a predefined location object that designates the location of the VoIP communications device or a reference to the location of the VoIP communications device. The call server receives the call initiation request and queries a VoIP Positioning Center (VPC). The VPC, in conjunction with a location information server (LIS) and an emergency routing database (ERDB), uses the location object or location reference to identify a public safety answering point (PSAP) that serves the location of the calling VoIP communications device.
The VPC returns an Emergency Services Routing Number (ESRN) and Emergency Services Query Key (ESQK) to the call server. Additionally, the VPC stores the TN of the calling VoIP communications device and its location in conjunction with the ESQK. The call server uses the ESRN to route to call to a gateway connected to a selective router that serves the selected PSAP. The selective router uses the ESQK to route the call to the selected PSAP and forwards the ESQK. The PSAP uses the ESQK to query the VPC via the incumbent emergency service provider's local automatic location information (ALI) database for the location of the calling communications device.
NENA (and others) are also developing specifications for emergency requests from VoIP networks that are delivered to a VoIP-enabled PSAP. At this point, NENA has developed requirement specifications, but has just begun defining call delivery methodology. In the current art, routing of an emergency services call from a VoIP communications device to an IP PSAP is based on the location object from the VoIP-enabled communications device or from a LIS in the VoIP service provider's network. The call is routed into an appropriate VoIP emergency services network based on the location object. The VoIP emergency services network uses the location object to route the call through the network to the appropriate IP PSAP.
A problem in the art is that neither the extant or proposed standards nor the current art provides a method for routing legacy business and residential subscribers of an incumbent local exchange carrier (ILEC) to an IP PSAP.